Certified Rhythm Analysis Technician (CRAT) Practice Exam

During the cardiac cycle, systole and diastole represent two critical phases of the heart's functioning. Systole refers to the phase when the heart muscles contract, leading to the ejection of blood from the heart into the arteries. This contraction occurs in both the atria and the ventricles, but primarily, it is the ventricles that contract during this phase, forcing blood out into the pulmonary artery and the aorta.

Conversely, diastole is the phase when the heart muscles relax. During this relaxation period, the heart chambers, particularly the atria, fill with blood returning from the body and lungs. This phase is crucial as it prepares the heart for the next contraction. Therefore, while the heart is undergoing diastole, there is an opportunity for blood to flow into the heart, setting the stage for the next cycle of systole.

Understanding this relationship between systole and diastole is essential because it highlights the dynamic nature of blood circulation and forms the basis for recognizing normal and abnormal cardiac function.